Oxygen isotopes of land snail shells in high latitude regions

Abstract

The present study investigates the environmental significance of the oxygen isotopic composition of several modern land snail species collected along two north-to-south transects in Alaska and Scandinavia at latitudes between 60 and 70 °N. We tested the hypothesis that land snail shell δ18O values primarily track precipitation δ18O. The results show that shell δ18O values from Scandinavia were ∼5.1‰ enriched in 18O with respect to snails from Alaska, equivalent to differences in precipitation δ18O values between the two regions. Within the Alaskan transect, shell δ18O values increased with observed increasing air temperature and precipitation δ18O, whereas shell δ18O values from Scandinavia did not correlate to instrumental climate data because of a reduced climatic gradient across the locations sampled. In addition, shell δ18O values differed significantly among sympatric species, with larger species consistently exhibiting higher δ18O values, which implies that species-level isotopic variations should be considered at the local and microhabitat scale. However, when snail shell δ18O values from this study are combined with previously published data from North America and Europe, we see evidence that shell δ18O values track precipitation δ18O across latitudes, even when different species are combined because climate gradients are greater than variations among taxa.